The present invention relates generally to an improved plug assembly and more particularly to a plug assembly that combines the dual functions of minimizing excessive fluid flows and backflows.
During the use of pneumatically actuated equipment, a rupture of the fluid conduit or a malfunction of associated equipment can result in an excessive fluid flow through the conduit. In addition to being wasteful, this excessive fluid flow can be dangerous to operating personnel who happen to be in the area. There are known devices for restricting the flow in the event of excessive pressure differentials across the device. Some of these are disclosed in U.S. Pat. Nos. 3,918,492; 3,756,272; and 3,729,023.
In fluid system it is frequently necessary to prevent backflow through the system. Such a need arises when a conduit filled with fluid under pressure is disconnected from the pressure source. This can cause a rapid and dangerous discharge of fluid as the conduit empties. In addition if the conduit is flexible, the discharge may cause dangerous motion of the conduit.
Separate check valves and flow limiting valves have been provided. However, it is believed that they do not represent the best combination of low cost construction, ease of assembly, and desirable operating characteristics. Various known valve arrangements are disclosed in U.S. Pat. Nos. 3,872,884; 3,122,162; 2,673,568; 2,411,392; 2,245,271 and 824,425.